MP3399-12-STRING, CASCADING WHITE LED DRIVER WITH STEP-UP CONTROLLER

MP3399 Rev. 1.0

www.MonolithicPower.com

6

3/27/2013

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© 2013 MPS. All Rights Reserved.

PIN FUNCTIONS

Pin #

Name

Description

1

NC

No Connect.

2

VIN

Supply Input. VIN supplies the power to the chip, as well as the step-up converter switch.

Drive VIN with a 5V to 28V power source. Must be locally bypassed.

3

VCC

The Internal 6V Linear Regulator Output. VCC provides power supply for the internal

MOSFET switch gate driver and the internal control circuitry. Bypass VCC to GND with a

ceramic capacitor.

4

COMP

Step-up Converter Compensation Pin. This pin is used to compensate the regulation

control loop. Connect a ceramic capacitor from COMP to GND.

5

EN

Enable Control Input. Do not let this pin float. It is recommended TO locally filter WITH a

0.1 μF ceramic capacitor.

6

DBRT

Brightness Control Input. To use external PWM dimming mode, apply a PWM signal on

this pin for brightness control. To use DC input PWM dimming mode, apply a DC voltage

range from 0.2V to 1.2V on this pin linearly to set the internal dimming duty cycle from 0%

to 100%. The MP3399 has positive dimming polarity on DBRT.

7

GND

Analog Ground.

8

OSC

Switching Frequency Set. Connect a resistor between OSC and GND to set the step-up

converter switching frequency. The voltage at this pin is regulated to 1.23V. The clock

frequency is proportional to the current sourced from this pin.

9

ISET

LED Current Set. Tie a current setting resistor from this pin to ground to program the

current in each LED string. The MP3399 regulates the voltage across the current setting

resistor. The regulation voltage is 1.22V. The proportion of the current through the ISET

resistor and the LED current is 1:1000.

10

BOSC

Dimming Repetition Set. This is the timing pin for the oscillator to set the dimming

frequency. To use DC input PWM dimming mode, connect a capacitor from this pin to

GND to set the internal dimming frequency. A saw-tooth waveform is generated on this

pin. To use external PWM dimming mode, connect a resistor from this pin to GND, and

apply the PWM signal on DBRT pin.

11

LED12

LED String 12 Current Input. This pin is the open-drain output of an internal dimming

control switch. Connect the LED String 12 cathode to this pin.

12

LED11

LED String 11 Current Input. This pin is the open-drain output of an internal dimming

control switch. Connect the LED String 11 cathode to this pin.

13

LED10

LED String 10 Current Input. This pin is the open-drain output of an internal dimming

control switch. Connect the LED String 10 cathode to this pin.

14

LED9

LED String 9 Current Input. This pin is the open-drain output of an internal dimming

control switch. Connect the LED String 9 cathode to this pin.

15

LED8

LED String 8 Current Input. This pin is the open-drain output of an internal dimming

control switch. Connect the LED String 8 cathode to this pin.